Fuel composition containing nu, nu&#39;-dimethyl phenylene diamine to prevent knocking



Patented June 30, 1953 FUEL COMPOSITION CONTAINING N,N-DI- .METHYLPHENYLENE DIAMINE TO PRE- VENT KNOCKING Maurice It. Barusch, Richmond,Calif., assignor to California Research Corporation, San'Francisco,Calif., a corporation ofrDelaware No Drawing. Application September 19,1949,

1 Serial No. 116,640

This invention relates to spark-ignition engine fuels; moreparticularly, to spark-ignition engine fuels boiling in the gasolineboiling range and having improved anti-knock characteristics andstability in the presence of light, and to a method of producing suchfuels. In an attempt to reach a level of higher power output of agasoline engine before knocking occurs, it has become the practice tosupercharge the engine. However, supercharging, as a means of obtainingincreased power output, is limited. A given fuel can tolerate only alimited amount of supercharging beyond which limit it knocksexcessively. By employing rich fuel-air mixtures, that is, fuel-airmixtures in which the proportion offuel to air is such that there is acomplete combustion of the fuel, a greater amount of supercharging canbe tolerated with a given fuel than if a lean mixture is employed. Thisexpedient also has its limitations in that when a certain richness isreached, the engine misfires and power output drops off.

In an effort to increase the power output still further before knockingoccurs, numerous antiknock agents are added to the base fuel. Tetraethyllead is one of the most important of the anti-knock agents which havebeen added to spark ignition-engine fuels. Other agents which have beenproposed are, for the most part, less effective than tetraethyl lead,and are more expensive. Despite the advantages of tetraethyl lead, itsuse is disadvantageous owing to several factors, such as its toxicityand its tendency to deposit lead compounds in carburetors,.manifolds,valves, cylinders or exhaust pipes.

In still further efforts to increase the power of fuels before knockingoccurs, special base fuels,

are manufactured by cracking, isomerization of straight-chain tobranched-chain hydrocarbons, and alkyla'g'iion of isoparafiins witholeiins. Judicious blending of stocks so prepared with one another, orwith straight-run distillates, has also contributed to upgrading basefuels. Even when anti-knock agents have been added to special basefuels, these fuels have not had sufi'icient anti-knock capacity toobtain the amount of power desired in such instances as airplanetakeoffs and rapid ascents.

Even by combining the advantages oftetra ethyl lead, superior basestocks and rich fuelair mixtures, it is difficult to meet the desiredaviation fuel requirements such as desired in'the take-off of heavilyloaded aircraft.

Fuels of the gasoline type have been rated by the CFR-ASTM-D357-43Tmethod and the? CFR-ASTM-Dfil-437 method. These methods are commonlyknown as the FF-2, and F-37.

9 Claims. (Cl. 44-56) 2 methods, respectively. The failure of the abovemethods to rate fuels dependably for certain purposes has led to thedevelopment of another method, designated as the CFR-AFD-F l-443 method,commonly called the F- l method;

A fuel which meets the requirements described hereinabove is disclosedin pending application ofFir-ey et al., Serial No. 792,349, nowabandoned. This application discloses a fuel composition forspark-ignition engines containing N-methylat'edphenylene-diamines addedin an amount sufficient to increase substantially the anti-knock valueof the fuel. While the fuel compositions disclosedin the Firey et a1.application are'fuels having unusually superior properties, they are notideal in all respects.

of the additives disclosed in the Firey et al. 'application, is exposedto daylight, a haze formation occurs with subsequent deposition of atarry-like precipitate.

It is an object of this invention to provide a fue1 suitable forcompression-ignition engines containing N,N'-dimethyl-p-phenylenediamine in suflicient amount substantially to raise the anti-knock valueof the fuel which does not form a haze upon exposure to light.

It is another object of the present invention to provide a method ofobtaining a light-stable fuel composition containing anti-knock oroctane improving additives including N,N-dimethyl-pphenylene diamine.

It is a particular object of this invention to provide a light-stablerich-mixturefuel.

Anotherobject of this invention is to provide; a light-stable fuelcontaining N,N'-dimethyl-p phenylene diamine that does not plugfuel-line filters.

It has been discovered that a motor fuel containingN,N'-dimethyl-p-phenylene diamine in a sufficient amount substantiallyto increase the molecule.

The base fuel may be any hydrocarbon fuel boiling in the gasolineboiling range, that is, having an ASTM (D-86') distillation with aninitial boiling point of about F. and a final boiling Y point of about400 F. The base fuel may be run petroleum distillate, acracked-petroleum dis- It has been found that when a fuel containingN,N'-dimethy1-p-phenylene diamine; one

tillate, an alkylate (such as sulfuric acid or HF isoparaffin-olefinalkylate), an aromatic fuel or a blend of two or more-of the abovefuels. Most advantageously, a base fuel is employed boiling within therange above prescribed, which is de 5 rived from petroleum. The fuelshould not oxidize readily upon standing, forms gums or poly- Vmerization products, or loses color upon standing, and should have anoctane rating not less than about 80 (by the F-2 method).

The base fuels may or may notcontain tetraethyl lead. The unleaded fuelsoffer the advantage of improved anti-knock ratings without thedeleterious effects of tetraethyl lead. On the other hand, the leadedfuels are especially useful as high-octane fuels. AsN,N-dimethylpphenylene diamine may be used to obtain ahighoctane fueland only small amounts Of tetraethyl leadare required in this fuel, thepresent invention obviates the disadvantages inherent in the useof;large quantities of lead (such as the deposition of lead compounds incarburetors, manifolds, valves, cylinders or exhaust pipes, and thetoxicity of lead) The additives which inhibit haze formation in fuelscontaining N,N'-dimethyl-p-phenylene diamine are alcohols, ketones, ormixtures thereof. The alcohols may have 2 through 4 carbon atoms in themolecule, such as: ethyl alcohol; propyl alcohol; isopropyl alcohol;n-butyl alcohol; isobutyl alcohol; secondary butyl alcohol; tertiarybutyl alcohol; and mixtures thereof.

The ketones in this-invention have 3 through'B carbon atoms'inthemolecule. The ketones may be straight-chained, branch-chained andcyclic orwa mixture of these three types of ketones such asacetone;diethyl ketone; methyl ethyl ketone; dibutyl ketone; di-isobutyl ketone;cyclohexanone, etc; and mixtures thereof.

The N,N'-dimethyl-p-phenylene diamine is used in amounts sufficient toimprove the antiknock value (the octane number) of the sparkignitionengine fuel; amounts: ranging from about 0.1 to about 10 per cent byweight, based on finished fuel, have been found desirable: while amountsnot less than about 0.3 per cent are generally preferred.

The amount of the additive added to a fuel containingN,N-dimethyl-p-phenylene diamine should be sufiicient to light stabilizethe fuel against the formation of haze. The haze-inhibiting additive maybe used in amounts such that theblended fuels containat least 2 per cent(by weight of the blended fuel) of the additive. The amount of the agentpresent in the blended fuel is generally 2 through 10 per cent by weightof the blended fuel with 2 through 4 per cent being generally preferred.

Blendingof the diamine, the additive, and the base fuel may beaccomplished by mixing the three components in a container and usingsuch heat and/or agitation as may be necessary, or a concentrate may beformed from the diamine and theradditive and then the concentrate may beblended with the base fuel.

In addition to anti-knock agents, the fuel composition may contain guminhibitors in amounts of about 0.001 to about 0.05 weight per cent suchas N-n butyl -para-amino phenol, N-isobutyl para-amino phenol, and2,6-ditertiary butyl-qmethyl phenol, etc. Also, the fuel may containmetal deactivators in small amounts such as 0.001 to about 0.05 weightper cent such as N,N'-disalicylidene-1,2-diamino propane, variouscorrosion inhibitors, and coloring agents, etc.

When tetraethyl. lead is used in the fuel composition, it is oftennecessary to add stabilizers for the tetraethyl lead compound.

The mechanism by which the haze forms in a N,N-dimethyl-p-phenylenediamine-containing fuel is not clearly understood. It is thought thatonce this haze begins to form, continued haze formation may occur evenin the absence of sunlight.

In. order to better understand this invention, the following example isgiven:

EXAMPLE A base fuel containing 35 per cent isoparafiinic alkylate, '7per cent isopentane, and, 58 per cent Midway California straight-rungasoline (composed essentially of naphthene and parailin hydrocarbonsand containing less than 5 volume per cent of aromatic hydrocarbons) wasblended both with 0.1 per cent and 0.5 per cent N,N'-dimethylp-phenylenediamine. A cc. sample of each blend was added, in a dark room, to aseries of glass test tubes set in a shielded rack. One tube from each ofthe blends was set asideand to eachof the others was added varyingamounts of methyl alcohol, diethyl ether, n-butanol, ethyl alcohol,methyl ethyl ketone, di-isobutyl ketone, tertiary butyl alcohol andacetone. This was likewise done in a dark room. The color of each of thetubes was observed. Then all Of the samples were placed in the brightdaylight (mid-day) and the color was observed after 10 and 20 min- 1utes.

The table which follows is a tabulation of the results obtained:

Table .Percent of .N,N-di methyl-p- 'phenylene v mine added Color UponExposure to Day-- g t, ime

Amount (Percent) Compound Added 20 Min.

Tertiarybutyl a1cohol None Methyl alcohol n-but ol Ethyl Methyl ethylketone Dlethyl ether Di-isobutyl ketone Acetone Tertiary butylalcohol-.. None Very dark. D

Di-isohutyl ketone Acetone Methyl ethyl ketone..-" Methyl'alcohol Verydark.

Hazy.

. Very dark.

OOOOOOOO OQOQOOOOO Diethyl ether The table clearly shows that a fuelcontaining N,N-dimethyl-p-phenylene diamine will become hazy uponexposure to daylight. Likewise, this table shows that methyl alcohol andcliethyl ether will not inhibit the formation of the haze. Ethylalcohol, n-butanol, methyl ethyl ketone, diisobutyl ketone and acetone,as is shown, prevented the formation of the haze; The tertiary butylalcohol, also, as can be seen from the table, has an inhibiting effect.The substance, that formed in the fuels with or without methyl alcoholor diethyl'ether after minutes of exposure to daylight appeared to be atar-like precipitate.

It is believed that the haze and the tar-like precipitate that forms infuels containing the phenylene diamine may possibly be an oxidized formof the N,N-dimethyl-p-phenylene diamine. Thus, it can be seen that ifsubstantial amounts of this haze or precipitate form in a fuel,reduction of the octane number of the fuel may occur. The ketones andalcohols, containing at least 2 carbon atoms per molecule, inhibit theformation of haze in a diamine-containing fuel and render a fuel that isstable in the presence of daylight.

The fuel composition of this invention may be used as an aviation fuelor automobile fuel, or as a fuel in other types of spark-ignitionengines.

While the fuel of this invention is especially desirable for usage underrich-mixture and supercharging conditions, it may likewise be used underlean-mixture conditions.

While various specific embodiments of the invention have beenillustrated and described, many modifications and adaptations maybe madewithout departing from this invention, and all such changes as areincluded within the scope of the claims are embraced thereby.

I claim:

1. A light-stable fuel comprising a major portion of hydrocarbonsboiling in the gasoline boiling range, a minor portion above 0.1% ofN-,N'- dimethyl-p-phenylene diamine sufficient substantially to increasethe octane rating of said hydrocarbons, and a minor portion of 2-10% ofat least one material selected from the group consisting of alcoholscontaining 2 through 4 carbon atoms per molecule and ketones containing3 through 8 carbon atoms per molecule sufiicient substantially toprevent formation of haze from said phenylene diamine in saidhydrocarbons upon exposure to daylight.

2. The light-stable fuel of, claim 1, wherein said material is ethylalcohol.

3. The light-stable fuel of claim 1, wherein said material is methylethyl ketone.

4. The light-stable fuel of claim 1, wherein said material is acetone.

5. A light-stable fuel comprising a major ill portion of hydrocarbonsboiling in the gasoline boiling range, above 0.1 to 10% by weight ofN,N'-dimethyl-p-phenylene diamine suflicient substantially to increasethe octane rating of said hydrocarbons, and 2 to 10% by weight of atleast one material selected from the group consisting of alcoholscontaining 2 through 4 carbon atoms per molecule and ketones containing3 through 8 carbon atoms per molecule sufficient substantially toprevent formation of haze from said phenylene diamine in saidhydrocarbons upon exposure to daylight. I

6. The light-stable fuel of claim 5, wherein saidN,N'-,dimethyl-p-phenylene diamine is present in an amount not less than0.3 per cent by weight.

7. The light-stable fuel of claim 5, wherein said material selected fromthe group consisting of alcohols and ketones is present in an amount of2 to 4 per centby weight.

8. A light-stable gasoline comprising a. major portion of hydrocarbonsboiling within the gasoline boiling range selected from the groupconsisting of isopentane, alkylate, straight run gasoline, aromatics,isoparafilnic alkylate, and above 0.1 to 10% ofN,N'-dimethyl-p-phenylene diamine suflicient substantially to increasethe octane rating of said hydrocarbons, and a minor portion of 2 to 10%of at least one material selected from the group consisting of alcoholscontaining 2 through 4 carbon atoms per molecule and ketones containing3 through 8 carbon atoms per molecule sufiicient substantially toprevent formation of haze from said phenylene diamine in saidhydrocarbons upon exposure to daylight.

9. In a fuel composition comprising hydrocarbons boiling in the gasolineboiling range and above 0.1% of N,N-dimethyl-p-phenylene diaminesufiicient substantially to increase the octane rating of saidhydrocarbons, the improvement which comprises rendering said compositionlight stable by adding at least 2% by weight of at least one materialselected from the group consisting of alcohols containing 2 through 4carbon atoms per molecule and ketones containing 3 through 8 carbonatoms per molecule suflicient substantially to prevent formation of hazefrom said phenylene diamine in said hydrocarbons upon exposure todaylight.

. MAURICE R. BARUSCH.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,571,862 Midgley Feb. 2, 1926 1,690,988 Marley et a1. Nov. 6,1928 2,120,244 Dryer June 14, 1938 2,443,569 Ruggles June 15, 19482,487,909 Von Bramer Nov. 15, 1949 2,504,361 Van Hartesveldt Apr. 18,1950

1. A LIGHT-STABLE FUEL COMPRISING A MAJOR PORTION OF HYDROCARBONS BOILING IN THE GASOLINE BOILING RANGE, A MINOR PORTION ABOVE 0.1% OF N,N''DIMETHYL-P-PHENYLENE DIAMINE SUFFICIENT SUBSTANTIALLY TO INCREASE THE OCTANE RATING OF SAID HYDROCARBONS, AND A MINOR PORTION OF 2-10% OF AT LEAST ONE MATERIAL SELECTED FROM THE GROUP CONSISTING OF ALCOHOLS CONTAINING 2 THROUGH 4 CARBON ATOMS PER MOLECULE AND KETONES CONTAINING 3 THROUGH 8 CARBON ATOMS PER MOLECULE SUFFICIENT SUBSTANTIALLY TO PREVENT FORMATION OF HAZE FROM SAID PHENYLENE DIAMINE IN SAID HYDROCARBONS UPON EXPOSURE TO DAYLIGHT. 